From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
This change allows the MMC host to be claimed in situations where the host
may or may not have already been claimed. Also 'mmc_try_claim_host()' is
now exported.
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Acked-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxx>
Cc: Ian Molton <ian@xxxxxxxxxxxxxx>
Cc: "Roberto A. Foglietta" <roberto.foglietta@xxxxxxxxx>
Cc: Jarkko Lavinen <jarkko.lavinen@xxxxxxxxx>
Cc: Denis Karpov <ext-denis.2.karpov@xxxxxxxxx>
Cc: Pierre Ossman <pierre@xxxxxxxxx>
Cc: Philip Langdale <philipl@xxxxxxxxx>
Cc: "Madhusudhan" <madhu.cr@xxxxxx>
Cc: <linux-mmc@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/mmc/core/core.c | 34 +++++++++++++++++++++++++---------
include/linux/mmc/core.h | 1 +
include/linux/mmc/host.h | 2 ++
3 files changed, 28 insertions(+), 9 deletions(-)
diff -puN drivers/mmc/core/core.c~mmc-allow-host-claim-release-nesting drivers/mmc/core/core.c
--- a/drivers/mmc/core/core.c~mmc-allow-host-claim-release-nesting
+++ a/drivers/mmc/core/core.c
@@ -461,16 +461,18 @@ int __mmc_claim_host(struct mmc_host *ho
while (1) {
set_current_state(TASK_UNINTERRUPTIBLE);
stop = abort ? atomic_read(abort) : 0;
- if (stop || !host->claimed)
+ if (stop || !host->claimed || host->claimer == current)
break;
spin_unlock_irqrestore(&host->lock, flags);
schedule();
spin_lock_irqsave(&host->lock, flags);
}
set_current_state(TASK_RUNNING);
- if (!stop)
+ if (!stop) {
host->claimed = 1;
- else
+ host->claimer = current;
+ host->claim_cnt += 1;
+ } else
wake_up(&host->wq);
spin_unlock_irqrestore(&host->lock, flags);
remove_wait_queue(&host->wq, &wait);
@@ -481,29 +483,43 @@ int __mmc_claim_host(struct mmc_host *ho
EXPORT_SYMBOL(__mmc_claim_host);
-static int mmc_try_claim_host(struct mmc_host *host)
+/**
+ * mmc_try_claim_host - try exclusively to claim a host
+ * @host: mmc host to claim
+ *
+ * Returns %1 if the host is claimed, %0 otherwise.
+ */
+int mmc_try_claim_host(struct mmc_host *host)
{
int claimed_host = 0;
unsigned long flags;
spin_lock_irqsave(&host->lock, flags);
- if (!host->claimed) {
+ if (!host->claimed || host->claimer == current) {
host->claimed = 1;
+ host->claimer = current;
+ host->claim_cnt += 1;
claimed_host = 1;
}
spin_unlock_irqrestore(&host->lock, flags);
return claimed_host;
}
+EXPORT_SYMBOL(mmc_try_claim_host);
static void mmc_do_release_host(struct mmc_host *host)
{
unsigned long flags;
spin_lock_irqsave(&host->lock, flags);
- host->claimed = 0;
- spin_unlock_irqrestore(&host->lock, flags);
-
- wake_up(&host->wq);
+ if (--host->claim_cnt) {
+ /* Release for nested claim */
+ spin_unlock_irqrestore(&host->lock, flags);
+ } else {
+ host->claimed = 0;
+ host->claimer = NULL;
+ spin_unlock_irqrestore(&host->lock, flags);
+ wake_up(&host->wq);
+ }
}
void mmc_host_deeper_disable(struct work_struct *work)
diff -puN include/linux/mmc/core.h~mmc-allow-host-claim-release-nesting include/linux/mmc/core.h
--- a/include/linux/mmc/core.h~mmc-allow-host-claim-release-nesting
+++ a/include/linux/mmc/core.h
@@ -139,6 +139,7 @@ extern unsigned int mmc_align_data_size(
extern int __mmc_claim_host(struct mmc_host *host, atomic_t *abort);
extern void mmc_release_host(struct mmc_host *host);
+extern int mmc_try_claim_host(struct mmc_host *host);
/**
* mmc_claim_host - exclusively claim a host
diff -puN include/linux/mmc/host.h~mmc-allow-host-claim-release-nesting include/linux/mmc/host.h
--- a/include/linux/mmc/host.h~mmc-allow-host-claim-release-nesting
+++ a/include/linux/mmc/host.h
@@ -182,6 +182,8 @@ struct mmc_host {
struct mmc_card *card; /* device attached to this host */
wait_queue_head_t wq;
+ struct task_struct *claimer; /* task that has host claimed */
+ int claim_cnt; /* "claim" nesting count */
struct delayed_work detect;
_
--
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